LONDON -- Bayer AG has been holding talks with Aventis SA on combining the two companies' blood businesses in a joint venture valued at about $1 billion (1.12 billion euros), people familiar with the situation say.

The discussions come as Bayer Chief Executive Manfred Schneider told Sueddeutsche Zeitung, a German daily newspaper, that the company's health-care division was in a number of talks that could involve partnerships based on individual products or even encompass the entire Bayer Health Care unit. "In one...